The influence of facade properties on the canopy layer microclimate within city blocks

Gál, Csilla V

2014 (English)Conference paper, Published paper (Other academic)

Abstract [en]

The application of high albedo surfaces and 'cool' materials — characterized by high solar reflectance and emissivity — are often advocated as a means to mitigate the urban heat island (UHI), to decrease indoor temperatures and consequently to reduce cooling loads in warm weather. The frequently described mechanism that links higher surface albedos with lower outdoor temperatures emphasizes the role of decreased surface temperatures in the process. Admittedly, the high albedo approach to UHI mitigation is primarily recommended for roofs, which, compared to roads and facades, have less obstructed sky views. During the day, the higher sky view factor of roofs prevents the trapping of radiation within the urban texture, and ensures a better radiative cooling by night. Nevertheless, the high albedo approach and the application of `cool materials' are increasingly recommended for both urban roads (Akbari, Pomerantz, and Taha 2001; Alchapar, Correa, and Cantón 2014; Santamouris et al. 2012; Santamouris, Synnefa, and Karlessi 2011; Synnefa et al. 2011; Zinzi, Carnielo, and Fasano 2012) and facades (Bougiatioti et al. 2009; Doya, Bozonnet, and Allard 2012; Synnefa, Santamouris, and Apostolakis 2007). The goal of this study is to investigate the role of facade surface properties on the canopy layer microclimate in a dense urban context.